Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
MUSCLE PHYSIOLOGY Muscular System Functions •Body movement •Maintenance of posture •Respiration •Production of body heat •Communication •Constriction of organs and vessels •Heart beat Properties of Muscle Contractility Ability of a muscle to shorten with force Excitability Capacity of muscle to respond to a stimulus Extensibility Muscle can be stretched to its normal resting length and beyond to a limited degree Elasticity Ability of muscle to recoil to original resting length after stretched Muscle Tissue Types Skeletal Attached to bones Striated, Voluntary and involuntary (reflexes) Smooth Walls of hollow organs, blood vessels, eye, glands, skin Not striated, involuntary, gap junctions in visceral smooth Cardiac Heart Striations, involuntary, intercalated disks Muscle fiber Internal organization: Sliding Filament Model I: Actin myofilaments sliding over myosin to shorten sarcomeres Actin and myosin do not change length Shortening sarcomeres responsible for skeletal muscle contraction During relaxation, sarcomeres lengthen Sliding filament model II: Energy Sources ATP provides immediate energy for muscle contractions from 3 sources Creatine phosphate During resting conditions stores energy to synthesize ATP Anaerobic respiration Occurs in absence of oxygen and results in breakdown of glucose to yield ATP and lactic acid Aerobic respiration Requires oxygen and breaks down glucose to produce ATP, carbon dioxide and water More efficient than anaerobic Slow and Fast Fibers Slow-twitch Contract more slowly, smaller in diameter, better blood supply, more mitochondria, more fatigueresistant than fast-twitch Fast-twitch Respond rapidly to nervous stimulation, contain myosin to break down ATP more rapidly, less blood supply, fewer and smaller mitochondria than slowtwitch Distribution of fast-twitch and slow twitch Most muscles have both but varies for each muscle Effects of exercise Hypertrophies: Increases in muscle size Atrophies: Decreases in muscle size Fatigue Decreased capacity to work and reduced efficiency of performance Types: Psychological Depends on emotional state of individual Muscular Results from ATP depletion Synaptic Occurs in neuromuscular junction due to lack of acetylcholine